Oct 6, 2015

Functional analysis of an unusual type IV pilus in the Gram-positive Streptococcus sanguinis

Molecular Microbiology
Ishwori GurungVladimir Pelicic

Abstract

Type IV pili (Tfp), which have been studied extensively in a few Gram-negative species, are the paradigm of a group of widespread and functionally versatile nano-machines. Here, we performed the most detailed molecular characterisation of Tfp in a Gram-positive bacterium. We demonstrate that the naturally competent Streptococcus sanguinis produces retractable Tfp, which like their Gram-negative counterparts can generate hundreds of piconewton of tensile force and promote intense surface-associated motility. Tfp power 'train-like' directional motion parallel to the long axis of chains of cells, leading to spreading zones around bacteria grown on plates. However, S. sanguinis Tfp are not involved in DNA uptake, which is mediated by a related but distinct nano-machine, and are unusual because they are composed of two pilins in comparable amounts, rather than one as normally seen. Whole genome sequencing identified a locus encoding all the genes involved in Tfp biology in S. sanguinis. A systematic mutational analysis revealed that Tfp biogenesis in S. sanguinis relies on a more basic machinery (only 10 components) than in Gram-negative species and that a small subset of four proteins dispensable for pilus biogenesis are essential ...Continue Reading

Mentioned in this Paper

Gram-Positive Bacteria
Zone
Bacterial Proteins
Type IV Pilus Biogenesis
Genes
Cell Motility
Uptake
Streptococcus
Arthrobacter sanguinis
Mutant Proteins

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